Figure 5
The frequency of residues at positions 283 and 526 in the PB2 of various subtypes of IAVs isolated from different hosts. Full-length PB2 sequences of IAVs isolated from avian, swine and human were obtained from the Influenza Sequences Database. Sequence alignment was performed by the Clustal W alignment method using the Megalign program. The percentage of the isolates possessing the indicated residues within each subtype was calculated and indicated by the colored area.